1. Cancer Research UK Health Behaviour Research Centre, Department of Epidemiology and Public Health, University College London, London, UK
2. Department of Surgery and Cancer, Imperial College London, London, UK
3. Computing and Stats Management, Cancer Research UK Centre for Epidemiology, Mathematics and Statistics, Wolfson Institute of Preventive Medicine, London, UK
4. Wolfson Endoscopy Unit, St Mark's Hospital, Harrow, UK